Convert fuel economy between US MPG, UK MPG, L/100km, and km/L — using exact reciprocal formulas, not approximations.
Enter a value to convert.
| US MPG | UK MPG | L/100km | km/L |
|---|---|---|---|
| 20 | ≈24.02 | ≈11.76 | ≈8.50 |
| 30 | ≈36.03 | ≈7.84 | ≈12.75 |
| 40 | ≈48.03 | ≈5.88 | ≈17.01 |
| 50 | ≈60.04 | ≈4.70 | ≈21.26 |
A fuel economy converter translates how efficiently a vehicle uses fuel between the units different countries use to report it. The United States and United Kingdom report miles per gallon (MPG), where a bigger number means better efficiency, while most of the rest of the world reports liters per 100 kilometers (L/100km), where a smaller number means better efficiency — the two scales run in opposite directions.
A US gallon (3.785411784 liters) is smaller than a UK/Imperial gallon (4.54609 liters), so the same real-world fuel economy produces a higher MPG number under the UK definition than under the US one. A car that gets 30 MPG in the US would show roughly 36 MPG using the UK gallon — the vehicle hasn't changed, only the unit has. Always check which gallon a published MPG figure is using before comparing cars from different countries.
MPG expresses distance traveled per unit of fuel; L/100km expresses fuel used per unit of distance. Because one is the inverse of the other, converting between them means dividing a constant by the value rather than multiplying by a fixed factor — and dividing by zero has no defined answer, which is why a value of 0 isn't accepted in any unit here.
Fuel economy conversions are useful when comparing a car's official MPG rating against a European or Asian model listed in L/100km, researching a vehicle from another country, planning a road trip budget, or understanding fuel efficiency claims in international car reviews and buying guides.
Divide 235.214583 by the US MPG value: L/100km = 235.214583 ÷ MPG(US). For UK (Imperial) MPG, divide 282.480936 instead. These constants come from converting gallons and miles into liters and kilometers.
No. A UK (Imperial) gallon is larger than a US gallon, so the same fuel economy reads as a higher MPG number in the UK than in the US for an identical vehicle. Always check which gallon a figure uses before comparing.
MPG measures distance per unit of fuel (more is better), while L/100km measures fuel per unit of distance (less is better). Converting between the two directions requires dividing into a constant rather than multiplying by a fixed factor.
Kilometers per liter is a metric fuel economy figure similar in spirit to MPG, but using kilometers and liters instead of miles and gallons. It moves in the same direction as MPG: a higher number means better fuel economy.
Every unit here is a ratio of distance to fuel (or fuel to distance). A value of 0 would require dividing by zero to convert, which has no defined result, so 0 is not an accepted input.
About 7.84 L/100km (235.214583 ÷ 30 ≈ 7.840486).
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